Fluid fuel burner



Match 19, 1940.- c. E. MORAN FLUID FUEL BURNER Filed Jan. 12, 1937INVENTOR. Clarance E. Moran BY y 4: Q

4 ATTORNEY Patented Mar. 19, 1940.

UNITED STATES PATENT OFF-ICE FLUID FUEL BURNER 5 Claims. This inventionrelates to fluid fuel'bumers and in particular to burners of the typewhich employ a burner-head in the form of a porous refractory diaphragm.

The broad idea of constructinga burner head in the form of a porousrefractory, diaphragm is old in the art of gas burning apparatus. F. C.Krause Patent 21,076 issued. August 3, 1858 and W. Bone et a1. Patent1,223,248 issued April 1'7,

1917 illustrate burner heads of this general type. In burners of thetype illustrated in. the Krause and Bone et a1. patents, in order tohave properv combustion, it is necessary to supply air andgas thecombustion of the fuel used.

The later inventors in this field recognized that the supplying of -acombustible or explosive-mixture of fuel might lead to ahazardouscondition in case of backfiring into the mixing chamber of the burnerand many of the later patents in this field were directed to ways andmeans for overcoming this hazardous condition.

For example: In Patent 1,225,381 issued to U. Wedge, May '8, 1917, aseries of cooling coils were provided in the diaphragm to prevent theinlet side of the diaphragm from becoming overheated and thus ignitingthe explosive mixture of fuel at the inlet side of the burner.

In Patent 1,313,196 issued to C. E. Lucke on August 12, 1919, it wasalso attempted to solve the same problem by providing means to cool thecombustible mixture before admitting the same to.-

with a fine mesh screen at its rear face to pre-, vent .backfiring ofthe burner, and .in Patent.

1,830,826 issued to F. J. Cox, November 10, 1931, the, diaphragm of theburner head is provided with portions of different porosity foraccomplishing the same result.

In all of the patents cited, the burners disclosed.

shown, it is difficult, if not impossible, to obtain uniform heatingover the entire area of the oper-- ating face of the burner withoutproducing flames above the diaphragm, v .9

In burners of any substantial size, there is tendency for the diaphragmto produce a flame in the locality opposite to the discharge end of theinlet feed pipe and with the arrangements shown in the first citedtwoprior art patents, the closer the mouth of thefeed pipe approaches tothe dia phragm, the g'reaterbecomes this tendency.

In the present invention, a relatively simple arrangement is provided toobviate the danger of backfiring of the burner and to insure at I thesame time uniform operation over the entire area of the exposed face ofthe diaphragm.

These highly desirableresults are accomplished by reducing .the volumeof free space behind the diaphragm to a minimum and by providing aplurality of small passageways incommunication with a large portion ofthe rear face of the diaphragm so that gas is supplied uniformlythroughout the area of the diaphragmwithout substantially reducing itsvelocity.

By reason of this arrangement, there is never present a very largeamount of combustible mixture at the. rear side of the diaphragm and thefuel that is present at the rear side of the diaphragm has sufficientvelocity so as to prevent rearward propagation of a flame or ignition ofsuch fuel.

vOne 0f the objects of this invention relates to the provision of aporous refractory diaphragm which isadapted to safely provide foruniform combustion. over the entire area of the operating-face of v theburner.

Another object of the invention relates to the provision'of a burnerhead of the type defined in which the danger of explosion of thecombustible mixture which is supplied to the burner is greatly reducedif not entirely obviated.

A further object of the invention relates to the provision .of a fluidfuel burner employing a burn-l newed without renewing the entirediaphragm.

Afurther object of the invention relates to the provision of a burner ofthe type defined eml ploying a-burnerhead in theform of a porousrefractory diaphragm which is configurated and arrangedso as to providefor substantially uniform fiow ofjfuel throughout the entire area of theoperating face of the diaphragm, while at the same time maintaining at arelatively low tem-. perature, the face of. the diaphragm opposite tothe operating side thereof.

These and other objects of the-invention will become more apparent andbetter understood in connection with the drawing which shows, merely byway of illustration, structure adapted for carrying out the objects ofthe invention.

In the drawing, Figure 1 is a central sectional view of a gas burnerillustrative of one form of the invention; Figure 2 is a sectional viewtaken on line 2-2, Figure 1; Figure 3 is a plan view of the underside ofthe burner shown in Figure 1, with the bottom of the burner casingremoved to more clearly illustrate the details of the burner diaphragm;Figure 4 is a central sectional view of a modified form of gas burner;Figure 5 is a sectional view taken on line 5-5, Figure 4; Figure 6 is aplan view of the underside of the burner shown in Figures 4 and 5;Figure 7 is a sectional view taken on line !1, Figure 8, of anothermodified form of burner; Figure 8 is a plan view of the burner which isshown in section in Figure 7; and Figure 9 is a central sectional viewof yet another modification of the invention.

The burnerillustrated in Figure 1 comprises a diaphragm in the form of aporous refractory block I which is received within a hollow casing 2,formed from sheet metal or any other suitable material. A conduit 3communicates with the interior of the bottom portion of the casingstructure, as shown in Figures 1 and 3. One of the corner edges of thediaphragm is cut away to define a passageway 4 which is normally incommunication with the conduit 3.

A series of grooves or channels 5, which are formed on one face of thediaphragm, communicate with the passageway 4 and with the conduit 3. Acombustible mixture of fluid fuel is supplied to the passageways 4 and 5by way of the conduit 3 and in this manner, the fuel is supplied to theoperating face 6 of the diaphragm at a substantially uniform pressurethroughout the entire area of the diaphragm so that upon its ignition,the entire exposed face 8 of the diaphragm will be raised to asubstantially uniform degree of incandescence after the burner has beenin operation a short time.

By arranging the burner in the manner described, it is possible tomaintain the quantity of combustible mixture behind the operating faceof the burner at a minimum, thus reducing the possibilities of adangerous explosion occurring in the combustible mixture before it burnsat the operating face of the burner.

The provision of a relatively large number of small passageways, such asthe passageways 4 and 5, also insures the maintenance of relatively highvelocities for the combustible mixture which is supplied to the burnerand this tends to obviate the dangers of an explosion taking placebecause the rate of gas flow may be maintained in this manner at ahigher rate than the rate of flame propagation in a direction counter tothe flow of the combustible mixture.

In the modification of the invention illustrated in Figures 4 to 6, theburner comprises a plurality of relatively thin porous refractory slabsI, 8 and III, which are carried in a casing structure ll having a bottomwall with a series of grooves or channels l2 which communicate with achannel l3 which is formed in one edge of the casing structure.

A conduit l4 communicates with the channel l3 and in this manneroperates to supply a combustible mixture of fluid fuel to the channelsl2. The slabs 1, Band ill of the diaphragm may be of the same or ofdifferent porosity. It has been found that a sectional diaphragm of thetype shown promotes uniformity of combustion at the operating face I! ofthe burner and this construction is also advantageous in that the slab Iis the only one which ordinarily is subjected to any wear ordeterioration and the same may be replaced with less expense than wouldbe incurred if a single block of the combined thickness of the threediaphragms were replaced.

In the forms of the invention illustrated in Figures 1 to 6, it is, ofcourse, understood that the number of passageways between the diaphragmand its casing may be varied from the number shown and as their numberis increased the cross-sectional area of each passageway would, ofcourse, be decreased so that for a relatively high number of passagewaysthe arrangement would approach the situation where .the rear side of thediaphragm would be separated slightly from the contiguous face of thecasing so as to define a single restricted passageway coextensive withthe entire area of the rear face of the diaphragm and thus define aminimum of free space between thediaphragm and its casing.

In the form of the invention illustrated in F 8- ures 7 and 8, acircular porous refractory diaphragm 20 is employed. The operating face2! of this burner is relatively fiat and the face 22 opposite thereto,is of conical configuration. The diaphragm is carried by a casingstructure 22 of similar shape to the diaphragm and a conduit 24communicates with the central conical portion thereof,

When a combustile mixture of fluid fuel is supplied by way of theconduit 24, the relatively thicker central portion of the diaphragmimpedes the flow of fuel through the diaphragm in a direction parallelto the axis of the conduit and thus serves to distribute the fluid fuelun'iformly throughout the area of the operating face 2| of the burner.

Figure 8 illustrates another modification of the invention in which theburner is provided with an annular porous refractory diaphragm 25carried by a casing structure 28 of annular configuration. A conduit 21communicates with the interior of the casing structure centrallythereof. The diaphragm 25 is provided with a porous disk 28 insertedabove the outlet of the conduit 21 and this disk is spaced a slightdistance above the bottom wall of the casing structure 28 to facilitatethe uniform distribution of the fluid fuel over its area.

The porosity of the disk 28 is slightly greater than the porosity of thediaphragm 25 and because of this, it operates to equalize the fuelpressure throoughout the diaphragm. and in this manner, insures uniformheating throughout the entire area of the operating face 38 of thediaphragm.

The use of the insert 28, which is less porous than the rest of thediaphragm, illustrates another modification of the invention in whichthe indicated portion 28 at the underside of the diaphragm is treatedwith a material to reduce its porosity, as for example, sodium silicateor any other suitable material which will not be affected by the heatand gases to which it is exposed.

The treated central portion-of the diaphragm serves to provide foruniform gas distribution throughout the entire area of the diaphragm inthe same manner as it is accomplished through the use of the disk 28.

The burners described herein are also adapted to use fuels other thangas. For example, atomized or vaporized liquid fuels and air may be usedin place of the suggested gas'and air mixtures.

The foregoing description and the accompanying drawing to which itrelates, describes what might be termed the preferred modes ofpracticing the invention. It is to be clearly understood, however, thatthe invention includes each and every novel feature or combination ofnovel features herein disclosed, subject only to the restrictions of theprior art, and that the invention may assume other forms and it is nottobe limited to the particular and specific structure shown and vdescribed herein.

rality of interconnected passageways communicating with said conduitmeans and located substantially parallel to the enclosed face of saiddiaphragm, the sides of said passageways being defined in part at leastby said diaphragm so that a relatively large area of theporous diaphragmis directly exposed to the gaseous fuel in the. passageways and the fuelfilters through the pores of the diaphragm and is thus substantiallyuni-. formly distributed over the entire area of the operating face ofthe diaphragm and produces a substantially uniform heating effectthereat when the burner is operated.

2. A burner as set forth in claim 1 characterized by the fact that thestated passageways are defined in part at least by the face of thecasing structure opposite the rear face of the diaphragm.

3. A burner as set forth in claim 1 characterized by the fact that thestated passageways are formed by and between the opposed faces of thediaphragm and the casing structure.

4. A burner as set forth in claim 1 characterized by the fact that thestated passageways are located between the opposed faces of thediaphragm and easing structure and are defined in part, at least bychannels formed in the rear face of the diaphragm.

5. A burner as set forth in claim 1 charactere ized by the fact that therear face of the stated diaphragm is substantiallyin contact withtheadjacent face of said casing structure and the stated passageways arelocated between the aforesaid faces of the diaphragm and casingstructure and are defined by channels formed in the face of the casingstructure which is in contact with the rear wall of the diaphragm.

CLARENCE E. MORAN.

